The experiments in this project are designed to locate catecholaminergic, particularly dopaminergic, terminals in the brains of rats which might be where intravenously administered d-amphetamine exerts a rewarding action. Two kinds of experiments are being used. In the first, advantage is taken of the fact that systemic administration of dopamine receptor blockers such as haloperidol increase the rate of self-administration of d-amphetamine. The rate increase presumably occurs because, by increasing the amount of amphetamine in his body, the rat can over-ride low doses of haloperidol. In these experiments, the haloperidol is microinjected directly into various brain sites. When a site is found where injections of haloperidol increase self-administration rate, that site will be a candidate for a site where amphetamine exerts reinforcing actions. In the second kind of experiment, rats are being trained to iotophoretically self-administer amphetamine and other agents directly into various brain sites. The maps of reinforcing sites obtained by the two experimental approaches should be compatible.